Conventionally, nitride semiconductor has been used or studied for a light emitting device or a high power semiconductor device. In the case of a nitride semiconductor light emitting device, a light emitting device in a wide color range from blue to orange can be fabricated. Recently, by utilizing the characteristics of the nitride semiconductor light emitting device, a blue or green light emitting diode or a bluish violet semiconductor laser has been developed. Japanese Patent Laying-Open No. 10-270804 has reported a light emitting device including an emission layer formed of GaNAs well layers/GaN barrier layers.
In the GaNAs/GaN emission layer described in Japanese Patent Laying-Open No. 10-270804, however, crystal phase separation of a hexagonal system having a high N concentration and a cubic system (zinc blende structure) having a low N concentration is liable to occur, and thus a light emitting device having a high luminous efficiency is hardly obtained.